Flexible polymeric film including reinforcement layer

ABSTRACT

A flexible polymeric film includes a reinforcement layer and a base layer. The reinforcement layer includes a lamella and a plurality of columns. The columns are on a surface of the lamella. Each of the columns extends in a direction and is separated from a neighboring column by a gap. The base layer is coupled to the columns and portions of the surface of the lamella in the gaps between the columns. The base layer is less rigid than the reinforcement layer. The flexible polymeric film can be produced by spraying a precursor onto a substrate. A layer of the precursor is formed on the substrate and exposed to an energy beam to form a preliminary film on the substrate. The columns can be formed from a plurality of portions of the preliminary film. The lamella is formed on top of the preliminary film that is formed with the columns.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/771,064, filed on Nov. 24, 2018; and U.S. ProvisionalPatent Application No. 62/798,974, filed on Jan. 30, 2019, which areincorporated by reference herein in their entirety.

BACKGROUND Field of the Disclosure

The present disclosure generally relates to polymeric films, andspecifically to a flexible polymeric film that includes a reinforcementlayer and a method of producing such a flexible polymeric film.

Description of the Related Arts

Thin polymeric films are playing an important role in technologicalapplications such as electronic packaging, optical coatings,lithographic resist layers, barrier layers, and so on. Mechanicalproperties of thin polymeric films are of paramount importance sincethese properties often impact many of the reliability issues encounteredwhile integrating the films into devices, such as electrical displaydevices. Conventional thin polymeric films have high flexibility but lowrigidity, which impairs their reliability for applications in thesedevices. For example, scratches or dents can be generated inconventional thin polymeric films when they are used as protection coverfilms of the flexible displays.

SUMMARY

Embodiments relate to a flexible polymeric film that includes areinforcement layer and a base layer. The reinforcement layer reinforcesmechanical properties of the flexible polymeric film. The reinforcementlayer includes a lamella and a plurality of columns. The columns are ona surface of the lamella. Each of the columns extends in a direction andis separated from a neighboring column by a gap. The base layer iscoupled to the columns and portions of the surface of the lamella in thegaps between the columns. The base layer is less rigid than thereinforcement layer.

In some embodiments, the flexible polymeric film is produced by sprayinga precursor onto a substrate. The precursor can include an organicmaterial and a metal-organic material. A layer of the precursor isformed on the substrate. The layer of the precursor can be exposed to anenergy beam, e.g., plasma radicals, e-beam, laser beam, and/orultraviolet (UV), to form a preliminary film on the substrate to form apreliminary film on the substrate. The columns can be formed from aplurality of portions of the preliminary film. The columns are morerigid than other portions of the preliminary film. The lamella is formedon top of the preliminary film that is formed with the columns.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the embodiments can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings.

FIG. 1A is a perspective view of a flexible polymeric film, inaccordance with an embodiment.

FIG. 1B is a cross-sectional view of the flexible polymeric film in FIG.1A, in accordance with an embodiment.

FIG. 2A illustrates a flexible polymeric film being bent downward, inaccordance with an embodiment.

FIG. 2B illustrates the flexible polymeric film being bent upward inaccordance with an embodiment.

FIG. 3 illustrates a schematic view of a film forming apparatus, inaccordance with an embodiment.

FIG. 4A is a timing diagram illustrating a process of forming columnsand a lamella of a flexible polymeric film by modulating plasma power,in accordance with an embodiment.

FIG. 4B is a timing diagram illustrating a process of forming columnsand a lamella of a flexible polymeric film by applying plasma and laserbeams, in accordance with an embodiment.

FIG. 4C is a timing diagram illustrating a process of forming columnsand a lamella of a flexible polymeric film by switching precursors, inaccordance with an embodiment.

FIG. 5A is a perspective view of a flexible polymeric film including apassivation layer, in accordance with an embodiment.

FIG. 5B is a cross-sectional view of the flexible polymeric film in FIG.5A, in accordance with an embodiment.

FIG. 6A is a cross-sectional view of a flexible polymeric film includinga stack of various layers, in accordance with an embodiment.

FIG. 6B is a cross-sectional view of another flexible polymeric filmincluding a stack various layers, in accordance with an embodiment.

FIG. 7 illustrates a lamella stack in accordance with an embodiment.

FIG. 8A is a cross-sectional view of a flexible polymeric film includingtwo sets of columns, in accordance with an embodiment.

FIG. 8B is a cross-sectional view of another flexible polymeric filmincluding two sets of columns, in accordance with an embodiment.

FIG. 9 is a flow chart illustrating a method for producing a flexiblepolymeric film, in accordance with an embodiment.

The figures depict various embodiments for purposes of illustrationonly.

DETAILED DESCRIPTION

In the following description of embodiments, numerous specific detailsare set forth in order to provide more thorough understanding. However,note that the embodiments may be practiced without one or more of thesespecific details. In other instances, well-known features have not beendescribed in detail to avoid unnecessarily complicating the description.

Embodiments are described herein with reference to the figures wherelike reference numbers indicate identical or functionally similarelements. Also in the figures, the left most digits of each referencenumber correspond to the figure in which the reference number is firstused.

Embodiments relate to a flexible polymeric film that has a reinforcementlayer for enhancing rigidity of the flexible polymeric film. Thereinforcement layer includes a lamella and discrete columns arranged ona surface of the lamella. Each of the columns extends in a direction andis separated from a neighboring column by a gap. The flexible polymericfilm also includes a base layer that provides flexibility. The baselayer is less rigid than the reinforcement layer. The base layer canhave an elasticity that is sufficient for providing a restorative forcewhen the flexible polymeric film is bent or deformed. The flexiblepolymeric film can be produced by spraying a precursor or successivespraying of precursors onto a substrate to form a layer of the precursoron the substrate. The layer of the precursor is exposed to an energybeam to form a preliminary film on the substrate. The columns can beformed from a plurality of portions of the preliminary film, resultingin an intermediate film. The intermediate film is the preliminary filmthat is formed with the columns. The columns are more rigid than otherportions of the preliminary film. The lamella is formed on top of theintermediate film to form the flexible polymeric film. The flexiblepolymeric film can have a smooth and flat surface, and be transparentfor optical applications, such as screen protection cover film, touchpanel, encapsulation, passivation, etc.

FIG. 1A is a perspective view of a flexible polymeric film 100, inaccordance with an embodiment. FIG. 1B is a cross-sectional view of theflexible polymeric film 100 in FIG. 1A, in accordance with anembodiment. A thickness T-f of the flexible polymeric film 100 is, forexample, in a range from 50 μm to 500 μm. The flexible polymeric film100 can be used on handheld or mobile devices, e.g., as a scratch-proofprotection cover. The flexible polymeric film 100 can also be used onnon-mobile device applications, such as monitors or TV. When used onnon-mobile device applications, the flexible polymeric film 100 can havea larger thickness T-f or other dimensions. A thickness T-f of theflexible polymeric film 100 is, for example, in a range from 100 μm to 1mm for devices with 10 inch by 10 inch or larger screen size. Otherdimensions may follow the ratios described herein. The flexiblepolymeric film 100 may include a reinforcement layer 110 and a baselayer 120.

The reinforcement layer 110 reinforces rigidity of the flexiblepolymeric film 100, e.g., it increases rigidity of the side of the filmwhere the reinforcement layer 110 is located. The reinforcement layer110 includes a lamella 130 and an array of columns 140 (referredindividually as “column 140”). The lamella 130 and columns 140 are morerigid than the base layer 120. The lamella 130 and columns 140 can havehigher Young's modulus than the base layer 120. The columns 140 are on asurface of the lamella. Each column 140 extends along the Z axis and isseparated from its neighboring column(s) 140 by a gap 150. In someembodiments, the flexible polymeric film 100 is rigid in a directionalong the Z axis and flexible in a different direction, such as adirection along the Y axis that is perpendicular to the Z axis. Theflexible polymeric film 100 can be bent or rolled in a direction alongthe Y axis. A restorative force can be generated in the flexiblepolymeric film 100 to restore the flexible polymeric film 100 to itsoriginal form, i.e. flat and/or non-deformed state, when the flexiblepolymeric film 100 is bent or rolled. For purpose of simplicityillustration, FIG. 1B shows three columns 140 and four gaps 150. FIG. 1Ashows more columns 140 and gaps 150. But the reinforcement layer 110 canhave a different number of columns 140.

In some embodiments, a width W-c of each column 140 can be larger than awidth W-g of the corresponding gap(s) 150. The width W-c of each column140 can be less than 500 micrometers (μm), e.g., in a range from 10 μmto 500 μm. The width W-g of each gap 150 can be less than 250 μm, e.g.,in a range from 1 μm to 250 μm. In some embodiments, the flexiblepolymeric film 100 is used on a display device, such as a touch screen.A user can use a tool, such as a pen, to interact with content displayedon the device. The width W-g of some or all the gaps 150 is smaller thana portion of the tool that contact the flexible polymeric film 100during the usage of the tool. The portion of the tool may be a tip orsharp edge that can potentially make scratches or dents on the flexiblepolymeric film 100. As W-g is smaller than the portion of the tool, theportion of the tool can contact a portion of the flexible polymeric film100 that includes at least a portion of a column 140. As the column 140is rigid, it can prevent the portion of the tool from making thescratches and dents.

In some embodiments, a ratio of a thickness T-c of the columns 140 to athickness T-1 of the lamella 130 is equal to or larger than 10. Thethickness T-1 of the lamella 130 can be in a range from 100 nanometers(nm) to 20 μm. A thickness T-r of the reinforcement layer 110 can be ina range from 1 μm to 500 μm.

The base layer 120 is less rigid than the reinforcement layer 110. Insome embodiments, the base layer 120 has a high elasticity, i.e. smallerelastic modulus, than the reinforcement layer 110. A surface of the baselayer 120 faces the reinforcement layer 110, contacts the columns 140and gaps 150, and is not flat. Another surface of the base layer 120that faces away from the reinforcement layer 110 is flat. The base layerincludes a polymer material, such as polyurethane, polyimide, a polymermaterial represented as R (or Polymer)-N═C—O-[cross-linking with Metal,C, N, O, H and its double bonds, and triple bonds], or a polymermaterial represented as R (or Polymer)-N═C—O-[cross-linking with Metal,C, N, S, O, H and its double bonds, and triple bonds].

In some embodiments, the reinforcement layer 110 is formed fromcross-linking molecules of the polymeric material of the base layer 120.Strong bonds between the reinforcement layer 110 and the base layer 120can be generated due to the increased cross-linking and transformationof the polymeric material in the base layer 120 to a more rigid phase inthe reinforcement layer 110. In some embodiments, the interface betweenthe reinforcement layer 110 and the base layer 120 (including theinterface between the lamella 130 and the base layer 120 and theinterface between the columns 140 and the base layer 120) are formedwith ionic bonds and/or covalent bonds by taking interstitial orsubstitutional atoms from neighboring molecules. Examples of the bondsinclude —(C═C)—, —(C≡C)—, —(C═N)—, —(C≡N), —(C—S)—, —(C═S), —(S—S)—,—(S═N)—, (S═S), (S═O), -(M-O)—, -(M=O), -(M=N)—, and -(M≡C)—, where M isa metal atom (e.g., Al, Zr, Sn, Ti, Ni, Ag, Cu, Mn, Co, Zn, In, Ga,etc.).

FIG. 2A illustrates a flexible polymeric film 200 being bent downward,in accordance with an embodiment. The flexible polymeric film 200includes a reinforcement layer 210 and a base layer 220. Thereinforcement layer 210 is on top of the base layer 220 and is morerigid than the base layer 220. The reinforcement layer 210 includes alamella 230 and columns 240 on a surface of the lamella 230. Anembodiment of the flexible polymeric film 200 is the flexible polymericfilm 100 described above in conjunction with FIGS. 1A and 1B.

As the flexible polymeric film 200 is bent downward, the reinforcementlayer 210 is under tensile stress and the base layer 220 is undercompressive stress. There are no cracks generated in the lamella 230 bythe bending, as the lamella 230 has high tensile strength, e.g., due tocross-linking of polymer molecules or elasticity of polymeric material.In some embodiments, the tensile strength of the lamella 230 decreaseswith its thickness. A thickness of the lamella 230 can be no more than20 μm, e.g., to allow the flexible polymeric film 200 to be bent. Aflexible polymeric film may have a radius smaller than 2 mm.

FIG. 2B illustrates the flexible polymeric film 200 being bent upward inaccordance with an embodiment. As the flexible polymeric film 200 isbent upward, the reinforcement layer 210 is under compressive stress andthe base layer 220 is under tensile stress. As the base layer 220 has ahigh elasticity, the polymer chains in the base layer 210 can bestretched elastically under the tensile stress and return their originalform after the tensile stress is removed. There are no cracks generatedin the base layer 220 during the bending. Due to the reinforcement layer210 plus the base layer 220 structure, the flexible polymeric film 200is free from cracks when it is bent along the Y direction, either upwardor downward.

FIG. 3 illustrates a schematic view of a film forming apparatus 300, inaccordance with an embodiment. The film forming apparatus 300 produces aflexible polymeric film 350 on a substrate 340. An embodiment of theflexible polymeric film 350 is the flexible polymeric film 100 describedabove. The substrate 340 can be plastic, membrane (organic and/orinorganic), fabric, non-gas permeable charge-transfer film or conductorfilm (e.g., Nefion), inorganic-organic hybrid film (e.g., metalconefilm), man-made hermetic film (e.g., encapsulating laminates orcomposites), thin metal or conducting transparent film, bio-substrate,or sacrificial film to be peeled off.

The film forming apparatus 300 includes a spraying module 310, a plasmamodule 320, and a cross-linking module 330. In the embodiment of FIG. 3,the film forming apparatus 300 remains stationary, and the substrate 340moves in a direction along the X axis from the spraying module 310towards the cross-linking module 330. In some other embodiments, thesubstrate 340 remains stationary and the film forming apparatus 300moves in a direction along the X axis.

The spraying module 310 sprays a precursor towards the substrate 340. Alayer of precursor 360 is formed on the substrate. In some embodiments,the precursor is a mixture of an organic precursor and a metal organicprecursor. Examples of the precursor includes metal containingprecursor, polyol, diisocyanate, coupling agents, silane coupling agentthat contains an organic function group (e.g., vinyl, chloro, epoxy,methacryloxy, mercapto, etc.) with a second functional group (e.g.,methoxy, ethoxy, etc.), polyurethane polyols, dianhydrides,diisocyanate, and silane coupling agent.

After the layer of precursor 360 is formed on a portion of the substrate340, the portion of the substrate 340 moves along the X axis toward theplasma module 320. The plasma module 320 forms a preliminary film 370from the layer of precursor 360, e.g., by solidifying the layer ofprecursor 360. In some embodiments, the plasma module 320 generatesplasma radicals and exposes the layer of the precursor 360 to the plasmaradicals to form the preliminary film 370. In some embodiments, thepreliminary film 370 has a thickness in a range from 50 μm to 500 μm.The plasma can be O₂, N₂O, H₂O, Ar, Na, or NH₃ plasma.

In some embodiment, the preliminary film 370 is formed by spraying anadditional precursor onto the layer of precursor 360 to form a layer ofthe additional precursor on top of the layer of the precursor 360. Theadditional precursor can be sprayed by a second spraying module that islocated between the spraying module 310 and the plasma module 320. Thepreliminary film 370 can be formed by exposing the layer of theadditional precursor to an energy beam, e.g., plasma radicals generatedby the plasma module 320.

In some embodiments, an initial film is formed by exposing the layer ofthe precursor 360 to an energy beam, e.g., the plasma radicals generatedby the plasma module 320. An additional precursor is sprayed, e.g., by asecond spraying module located between the plasma module 320 and thecross-linking module 330, to form a layer of the additional precursor.The layer of the additional precursor can be exposed to an energy beam,e.g., plasma radicals generated by a second plasma module locatedbetween the second spraying module and the cross-linking module 330, toform the preliminary film 370.

In one embodiment, the precursor sprayed by the spraying module 310 isan organic precursor and the precursor sprayed by the second sprayingmodule is a metal organic precursor. In another embodiment, theprecursor sprayed by the spraying module 310 is a metal organicprecursor and the precursor sprayed by the second spraying module isanother metal organic precursor. In yet another embodiment, theprecursor sprayed by the spraying module 310 is an organic precursor andthe precursor sprayed by the second spraying module is another organicprecursor.

The cross-linking module 330 forms columns 380 (referred individually as“column 380”) and a lamella 390 from portions of the preliminary film370, thereby forming the flexible polymeric film 350 is thereby formed.The columns 380 and lamella 390 are more rigid than the rest of theflexible and elastic polymeric film 350.

In some embodiments, the cross-linking module 330 forms the columns 380through cross-linking of molecules of one or more materials of thepreliminary film 370. Thus, the columns 380 has a higher degree ofcross-linking than other portions of the preliminary film 370. Forexample, the cross-linking module 330 exposes the portions of thepreliminary film to an energy beam, such as plasma radicals, and theplasma radicals cause the cross-linking. The plasma radicals canpenetrate the top surface of the preliminary film 370. The plasmaradicals can break the C—H bonds in the material of the preliminary film370 and form different bonds, such as C═C, C≡C, N—H, N═N, N═N, C═N, C≡N,S—S, S═S, or S═O bonds. The plasma radicals include oxygen-based plasmaradicals. The cross-linking module 330 can use a higher plasma power toform the columns 380 than the plasma power used by the plasma module 320for forming the preliminary film 370.

In some embodiments, the cross-linking module 330 forms the columns 380by exposing the portions of the preliminary film to laser beams,electron beams, or ultraviolet (UV) irradiation. The laser beams,electron beams, or UV irradiation can generate more bonds, such as-(M-O)—, -(M=O), -(M=N)—, -(M≡C), -(M=C)—, or -(M≡C)—. These bondsresult in increase in tensile strength, impact strength, and materialstrength. The cross-linking module 330 can control the width andthickness of the columns 380 and the width of gas between the columns380 by controlling intensity and/or exposing time of the laser beams,electron beams, or UV irradiation, or moving speed of the substrate 340.It can also control extending direction of cross-linking in the columns380 by controlling injection direction of the laser beams, electronbeams, or UV irradiation. The cross-linking module 330 can also controlthe direction of the columns 380 by controlling configuration ofelectrodes that generate plasma radicals, injection direction of laserbeams or electron beams, etc. As shown in FIG. 3, the columns 380 extendin a direction that is perpendicular to the direction where thesubstrate 340 moves, i.e., a direction along the X axis in FIG. 3. Inother embodiments, the cross-linking module 330 can form columns thatextend in a direction parallel to the direction where the substrate 340moves.

In some embodiments, the cross-linking module 330 forms the lamella 390by exposing the preliminary film formed with the columns 380 to plasmaradicals, laser beams, or electron beams to cause cross-linking ofmolecules. The lamella 390 thereby has a higher degree of crosslinkingthan the preliminary film and is more rigid.

In some other embodiments, the cross-linking module 330 sprays a secondprecursor (e.g., metal-organic precursor) onto the preliminary filmformed with the plurality of columns 380. The second precursor can bethe same as or different from the precursor sprayed by the sprayingmodule 310. Examples of the second precursor includes DiMethylAluminumIsopropoxide (DMAI), DMAON (C₁₁H₂₆AlON),3-((Dimethylanimo)Propyl)Aluminumum) (DMPA), and Trimethyl aluminum(TMA) as a precursor of Al-incorporated film; Dimethyldichlorosilane(DMDCS), (dimethylamino)tri-methylsilane (DMATMS), hexamethyldisilazane(HMDS), and bis (dimethylamino)dimethylsilane (BDMADMS) forSi-incorporated film; Tetrakisdimethylaminotitanium (TDMAT) and tetrakisethylmethylaminotitanium (TEMAT) for Ti-incorporated film. The secondprecursor may be a metal organic precursor that includes metal atomssuch as Zr, Zn, Ni, Ag, Ta, W, etc.

The cross-linking module 330 further generates plasma and exposes thelayer of the second precursor to the plasma to transfer it to thelamella 390. The plasma can be oxygen based plasma. In some embodiments,the second precursor is a metal-organic precursor, and the plasma causesoxidation, nitridation, or carbonization of the metal-organic precursor.

The cross-linking module 330 can enhance rigidity of the lamella 390through an infiltration or impregnation process. For instance, thecross-linking module 330 form a composite layer through infiltration orimpregnation of a metal-contained precursor into the lamella 390. Themetal-contained precursor can be a metal-organic precursor of Alucone,Titanicon, Zircone, Silicone, Zincone, etc.

The cross-linking module 330 may form multiple lamellae. Each of thelamellae can have an orientation that is perpendicular to theorientation of its neighboring lamella(s). The orientation of a lamellais an orientation of cross-linking in the lamella. The lamellae havingthose different orientations can be formed by rotating the substrate 340by 90 degrees after forming each lamella. For example, two lamellaeeither in plane with 90 degree rotated each other or perpendicular. Thecross-linking module 330 may form an odd number of lamellae to avoidwarping, as the flexible polymeric film 350 can have high stiffness in adirection perpendicular to the orientation of the top lamella. Thestructure of having multiple lamellae with different orientations canprevent moisture and/or gas penetration into the flexible polymeric film350, result in better dimensional stability, minimize the chance ofoverlap or connections of pinholes within the lamellae, and achieveconsistent mechanical strength across all directions. Neighboringlamellae can be separated by a layer of polymeric material, such as thepolymeric material of the preliminary film 370.

FIG. 4A is a timing diagram illustrating a process of forming columnsand a lamella of a flexible polymeric film by modulating plasma power,in accordance with an embodiment. The process can be performed by thefilm forming apparatus 300 in FIG. 3 to form the columns 380 and lamella390. FIG. 4A shows plasma power as a function of time for threeprocesses 410, 420, and 430.

In the process 410, the film forming apparatus 300 continuously exposesthe layer of precursor 360 to plasma radicals having a plasma power 415to form the preliminary film 370.

In the process 420, the film forming apparatus 300 alternatively exposesthe preliminary film 370 to plasma radicals having a plasma power 425and plasma radicals having a plasma power 427 to form the columns 380from portions of the preliminary film 370. The plasma power 427 ishigher than the plasma power 425. The plasma power 427 is high enough tocause cross-linking of molecules of the polymeric material in thepreliminary film 370. The plasma power 425 can be equal to the plasmapower 415 in the process 410. The film forming apparatus 300 can applythe plasma power 427 to a portion of the preliminary film 370 where acolumn 380 is intended to be formed, and apply the plasma power 425 to aportion of the preliminary film 370 where no column 380 is intended tobe formed. The columns 380 have a higher degree of cross-linking and aremore rigid than the rest of the preliminary film 370.

In the process 430, the film forming apparatus 300 exposes thepreliminary film 370 formed with the columns 380 to plasma radicalshaving a plasma power 435 to form the lamella 390. The plasma power 435is also high enough to cause cross-linking of molecules of the polymericmaterial in the preliminary film 370 so that the lamella 390 also has ahigher degree of cross-linking and are more rigid than the rest of thepreliminary film 370. The plasma power 435 can be equal to the plasmapower 427 in the process 420.

FIG. 4B is a timing diagram illustrating a process of forming columnsand a lamella of a flexible polymeric film by applying plasma and laserbeams, in accordance with an embodiment. The process can be performed bya film forming apparatus, such as the film forming apparatus 300 in FIG.3 to form the columns 380 and lamella 390. FIG. 4B shows plasma power asa function of time for three processes 440, 450, and 460. The processes440 and 460 can be the same as the processes 410 and 430 in FIG. 4A,respectively. For instance, the plasma power 445 is the same as theplasma power 415, and the plasma power 465 is the same as the plasmapower 435. But the process 450 is different from the process 420.

In the process 450, the film forming apparatus 300, particularly thecross-linking module 330, injects laser beams towards portions of thepreliminary film 370 to form the columns 380. The laser power alternatesbetween on and off. The laser power is on when a portion of thepreliminary film 370 from which a column is intended to be formed isunder the cross-linking module 330. Likewise, the laser power is offwhen a portion of the preliminary film 370 from which no column isintended to be formed is under the cross-linking module 330.

FIG. 4C is a timing diagram illustrating the process of forming columnsand a lamella of a flexible polymeric film by switching precursors, inaccordance with an embodiment. The process can be performed by a filmforming apparatus, such as the film forming apparatus 300 in FIG. 3 toform the columns 380 and lamella 390. FIG. 4C shows plasma power as afunction of time for three processes 470, 480, and 490. During theprocesses 470, 480, and 490, the substrate 340 is exposed to a plasma,such as oxygen based plasma.

In the process 470, the film forming apparatus 300 continuously sprays aprecursor 475 towards the substrate 340 to form a layer of precursor360. The plasma transfers the layer of precursor 360 to the preliminaryfilm 370. In one embodiment, the precursor 475 is a precursor forPolyol/Isocyanate.

In the process 480, the film forming apparatus 300 alternatively spraysthe precursor 475 and a different precursor 485 to the preliminary film370. The plasma transfers the precursor 485 to the columns 380 andtransfers the precursor 475 to a polymeric material of the preliminaryfilm 370 between the columns 380, i.e., gaps between the columns 380. Insome embodiments, the precursor 485 is a precursor for alumina.

In the process 490, the film forming apparatus 300 continuously spraysthe precursor 485 to the preliminary film 370 formed with the columns380. The plasma transfers the precursor 485 to the lamella 390, e.g., bysolidifying a layer of the precursor 485.

FIG. 5A is a perspective view of a flexible polymeric film 500 includinga passivation layer 550, in accordance with an embodiment. FIG. 5B is across-sectional view of the flexible polymeric film 500 in FIG. 5A, inaccordance with an embodiment. The flexible polymeric film 500 alsoincludes reinforcement layer 510 and a base layer 520. The reinforcementlayer 510 includes a lamella 530 and columns 540 on a surface of thelamella 530. An embodiment of the reinforcement layer 510 is thereinforcement layer 110, and an embodiment of the base layer 520 is thebase layer 120 discussed above.

The passivation layer 550 has a higher elasticity, i.e. smaller elasticmodulus, than the reinforcement layer 510. The passivation layer 550 canaccommodate stress applied on the flexible polymeric film 500, such asstress caused by bending, rolling, or folding the flexible polymericfilm 500. The passivation layer 550 is on another surface of the lamella530 that faces away from the columns 540, i.e., the surface of thelamella 530 opposing the surface where the columns 540 are. In someembodiments, the passivation layer 550 has a thickness T-p along the Yaxis in a range from 100 nm to 10 μm. The passivation layer 550 can betransparent to light, and can be an oleophobic coating, transparentconducting layer (e.g., ITO (Indium Tin Oxide) or SnO₂), self-healingsulfur vulcanized polymer layer, or cross-linked Metalcones. Thepassivation layer 550 can be durable and scratch-resistant. For example,the passivation layer 550 can be a hard coating (e.g., Al₂O₃, Al—Si—O,Al—Ti—O, Al—Zr—O, ZrO₂, TiO₂, Diamond Like Coating).

FIG. 6A is a cross-sectional view of a flexible polymeric film 600including a stack of various layers in the Y-Z plane, in accordance withan embodiment. The flexible polymeric film 600 includes a passivationlayer 610, a lamella 620, a column 630, and a base layer 640. Theflexible polymeric film 600 can be an embodiment of the flexiblepolymeric film 500. In some embodiments, the flexible polymeric film 600does not include the passivation layer 610 or lamella 620. Thepassivation layer 610, lamella 620, column 630, and base layer 640 havea same length along the X axis. The column 630 extends along the wholebases layer 640. The flexible polymeric film 600 includes other columnsextending along the Z axis that are parallel to the column 630, andthese columns are separate from each other with a gap.

FIG. 6B is a cross-sectional view of another flexible polymeric film 650including a stack various layers in the X-Y plane, in accordance with anembodiment. The flexible polymeric film 650 includes a passivation layer660, a lamella 670, a column 680, and a base layer 690. The flexiblepolymeric film 600 can be an embodiment of the flexible polymeric film500. In some embodiments, the flexible polymeric film 650 does notinclude the passivation layer 660 or lamella 670. The passivation layer660, lamella 670, and base layer 680 have a same length along the Xaxis, but the column 680 has a shorter length. The column 680 extendsalong a portion of the base layer 680. The flexible polymeric film 650includes other columns extending along the Z axis that are parallel tothe column 680, and these columns are separate from each other with agap.

FIG. 7 illustrates a lamella stack 700, in accordance with anembodiment. The lamella stack 700 can be a part of a flexible polymericfilm. The flexible polymeric film can also include columns, such as thecolumns 140, that extend on a surface of the lamella stack 700 and abase layer, such as the base layer 120, that is coupled to the columnsand portions of the surfaces of the lamella stack 700 in gaps betweenthe columns.

The lamella stack 700 includes lamellae 710, 720, and 730. Each of thelamellae 710, 720, and 730 has an orientation that is perpendicular tothe orientation of its neighboring lamella or lamellae. The orientationof a lamella is an orientation of cross-linking in the lamella.Neighboring lamellae have perpendicular orientations. As shown in FIG.7, the lamella 710 and 730 each has an orientation along the Y axis, andthe lamella 720 has an orientation along the X axis. In some otherembodiments, one or more of the lamellae can have an orientation alongthe Z axis. For instance, the lamellae 710 and 730 can have anorientation along the Z axis, or the lamellae 710 and 730 each has anorientation that is 90 degrees rotation about the Z axis. The structureof having multiple lamellae with different orientations can preventmoisture and/or gas penetration, result in better dimensional stability,minimize the chance of overlap or connections of pinholes within thelamellae, and achieve consistent mechanical strength across alldirections.

The lamella stack 700 includes three lamellae 710, 720, and 730. Inother embodiments, a lamella stack can have a different odd number oflamellae, such as five, seven, etc. An odd number of lamellae can avoidwarping, as the lamella stack has high stiffness or rigidity in adirection perpendicular to the orientation of the top lamella. Takingthe lamella stack 700 for example, it has high stiffness or rigidityalong the X axis, which is perpendicular to the orientation of thelamella 710. In some embodiments, the top lamella and the bottom lamellahave the same orientation, degree of cross-linking, and/or thickness. Alamella between the top and bottom lamellae can have a differentthickness. A thickness of a lamella can be in a range from 1 nm to 1 μm.The top and bottom lamellae, such as the lamellae 710 and 730, can eachhave a thickness in a range from 10 nm to 1 μm. The intermediatelamellae, such as the lamella 720, can have a thickness in a range from25 nm to 10 μm.

As shown in FIG. 7, the lamellae 710, 720, and 730 are separated bypolymeric layers 740 and 750. Each polymeric layer includes a polymermaterial, which can be the same polymer material of the base layer ofthe flexible polymeric film. The lamellae 710, 720, and 730 can begenerated by cross-linking molecules of the polymer material. In someembodiments, the lamellae 710, 720, and 730 can have different degreesof cross-linking. The polymeric layers 740 and 750 provide mechanicalflexibility. They also function as barriers for gas and moisturepermeation from the ambient. The lamella stack 700 may include twopolymeric layers 740 and 750, or it may form with lamellae without thepolymeric layers 740 and 750 if the lamellae have mechanicalflexibilities. In other embodiments, a lamella stack can have adifferent even number of polymeric layers, such as four, six, etc. Thetop and bottom polymeric layers can be produced through the sameprocess, and they can have same physical properties such as thicknessand chemical composition. A thickness of a polymeric layer can be in arange from 1 nm to 1 μm. The top and bottom polymeric layers can have athickness in a range from 10 nm to 1 μm, and the other polymeric layerscan have a thickness in a range from 1 nm to 100 nm.

Chemical bonds can be formed in each polymeric layer and the lamellaeneighboring the polymeric layer. Examples of the chemical bonds include—(C═C)—, —(C≡C)—, —(C═N)—, —(C≡N), —(C—S)—, —(C═S), —(S—S)—, —(S═N)—,(S═S), (S═O), -(M-O)—, -(M=O), -(M=N)—, and -(M≡C)—, where M is a metalatom, e.g., Al, Zr, Sn, Ti, Ni, Ag, Cu, Mn, Co, Zn, In, Ga, etc.

FIG. 8A is a cross-sectional view of a flexible polymeric film 800including two sets of columns 810 and 820, in accordance with anembodiment. An embodiment of the columns 810 can be the columns 140. Thecolumns 810 are on a surface of a lamella 830. An embodiment of thelamella 830 can be the lamella 130 illustrated in FIGS. 1A and 1B. Thegaps between the columns 810 and the gaps between the columns 820 arefilled with a polymeric material 850. The columns 810 and 820 can beformed through cross-linking of molecules of the polymeric material 840.The columns 810 and 820 have higher degree of cross-link than the gas,and therefore have different optical properties from the gaps.

The columns 820 have a reverse shape of the columns 810. As shown inFIG. 8A, each gap between the columns 820 is below a column 810, andeach column 820 is below a gap between the columns 810. The columns 820can reduce optical distortions caused by the columns 810. Taking light850 and 860 for example, they both go through the flexible polymericfilm 800 from bottom to top but go through different portions of theflexible polymeric film 800. The light 850 goes through a gap betweentwo columns 820, a column 810, and the lamella 830. The light 860 goesthrough a column 820, a gap between two columns 810, and the lamella830. But with the design of the flexible polymeric film 800, both light850 and 860 go through a column, a gap, and the lamella 830. Theflexible polymeric film 800 can be placed on top of a display screen asa protective cover and it does not cause (or it can minimize) opticaldistortions in images presented by the display screen.

FIG. 8B is a cross-sectional view of another flexible polymeric film 870including two sets of columns, in accordance with an embodiment. Inaddition to the components of the flexible polymeric film 800, theflexible polymeric film 870 also includes another lamella 880, on whichthe columns 820 are arranged. Like the flexible polymeric film 800, theflexible polymeric film 870 does not cause optical distortions.

FIG. 9 is a flow chart illustrating a method for producing a flexiblepolymeric film, in accordance with an embodiment. The method can beperformed by the film forming apparatus 300 in FIG. 3. The method mayinclude different or additional steps than those described inconjunction with FIG. 9 in some embodiments or perform steps indifferent orders than the order described in conjunction with FIG. 9.

The film forming apparatus 300 sprays 910 a precursor onto a substrate.The precursor is a mixture of an organic precursor and a metal-organicprecursor. A layer of the precursor is formed 920 on the substrate.

The film forming apparatus 300 forms 930 a preliminary film on thesubstrate from the layer of the precursor. In some embodiments, thepreliminary film is formed by exposing the layer of the precursor to anenergy beam, such as plasma radicals, laser beam, e-beam, and/or UV. Forexample, the layer of the precursor is solidified by the energy beam,for example, through chemical reactions between the plasma radicals andthe precursor. In some other embodiments, the preliminary film is formedby spraying an additional precursor onto the layer of the precursor toform a layer of the additional precursor and exposing the layer of theadditional precursor to an energy beam. In yet some other embodiments,the preliminary film is formed by exposing the layer of the precursor toplasma radicals to form an initial film, spraying an additionalprecursor onto the initial film to form a layer of the additionalprecursor, and exposing the layer of the additional precursor to anenergy beam.

The film forming apparatus 300 forms 940 a plurality of columns from aplurality portions of the preliminary film. The plurality of columns ismore rigid than other portions of the preliminary film. The film formingapparatus 300 can form the columns through cross-linking molecules ofone or more materials of the preliminary film. In some embodiments, thefilm forming apparatus 300 exposes the plurality portions of thepreliminary film to an energy beam to transform the plurality portionsof the preliminary film to the plurality of columns.

The film forming apparatus 300 forms 950 a lamella on top of thepreliminary film formed with the plurality of columns. In someembodiments, the film forming apparatus 300 sprays a second precursoronto the preliminary film formed with the plurality of columns. A layerof the second precursor is formed on top of the preliminary film formedwith the plurality of columns. The film forming apparatus 300 exposesthe layer of the second precursor to a energy beam to transform thelayer of the second precursor to the lamella. In some embodiments, thefilm forming apparatus 300 exposes the preliminary film formed with theplurality of columns to plasma radicals, laser, or electrons totransform a top portion of the preliminary film formed with theplurality of columns to the lamella.

The language used in the specification has been principally selected forreadability and instructional purposes, and it may not have beenselected to delineate or circumscribe the inventive subject matter. Itis therefore intended that the scope of the disclosure be limited not bythis detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsis intended to be illustrative, but not limiting, of the scope of thedisclosure, which is set forth in the following claims.

What is claimed is:
 1. A flexible polymeric film comprising: areinforcement layer comprising: a lamella having a surface, and aplurality of columns on the surface of the lamella, each of theplurality of columns separated from a neighboring column by a gap andextending in a direction; and a base layer coupled to the plurality ofcolumns and portions of the surface of the lamella in gaps between theplurality of columns, the base layer less rigid than the reinforcementlayer.
 2. The polymeric film of claim 1, wherein a width of each of theplurality of columns of the reinforcement layer is larger than the gap.3. The polymeric film of claim 2, wherein a width of each of theplurality of columns is at most 500 nanometers.
 4. The polymeric film ofclaim 1, wherein a distance between each of the plurality of columns andthe neighboring column is at most 250 nanometers.
 5. The polymeric filmof claim 1, wherein a thickness of the lamella is from 100 nanometers to20 micrometers.
 6. The polymeric film of claim 1, wherein a ratio of athickness of the column to a thickness of the lamella is equal to orlarger than
 10. 7. The polymeric film of claim 1, wherein a surface ofthe base layer facing away from the reinforcement layer is flat, and athickness of the polymeric film is from 50 micrometers to 500micrometers.
 8. The polymeric film of claim 1, wherein the flexiblesubstrate is flexible in another direction that is perpendicular to thedirection.
 9. The polymeric film of claim 1, further comprising apassivation layer, the passivation layer having a higher elasticity thanthe reinforcement layer and arranged on a second surface of the lamella,the second surface of the lamella opposing the surface of the lamellawhere the plurality of columns are.
 10. The polymeric film of claim 9,wherein the passivation layer has a thickness from 100 nanometers to 1micrometer.
 11. The polymeric film of claim 1, further comprising aplurality of secondary columns, each of the plurality of secondarycolumns arranged below the gaps for reducing optical distortions causedby the plurality of columns.
 12. The polymeric film of claim 1, furthercomprising one or more additional lamellae, at least one of the one ormore additional lamellae having a first cross-linking directiondifferent from a second cross-linking direction of the lamella.
 13. Amethod for producing a flexible polymeric film, the method comprising:spraying a precursor onto a substrate; forming a layer of the precursoron the substrate; forming a preliminary film on the substrate from thelayer of the precursor; forming a plurality of columns from a pluralityportions of the preliminary film, the plurality of columns more rigidthan other portions of the preliminary film; and forming a lamella ontop of the preliminary film formed with the plurality of columns. 14.The method of claim 13, wherein forming a plurality of columns from aplurality portions of the preliminary film comprises: forming aplurality of columns from a plurality portions of the preliminary filmthrough cross-linking molecules of one or more materials of thepreliminary film.
 15. The method of claim 13, wherein forming aplurality of columns from a plurality portions of the preliminary filmcomprises: exposing the plurality portions of the preliminary film toplasma radicals, laser, electron beams, or ultraviolet to transform theplurality portions of the preliminary film to the plurality of columns.16. The method of claim 13, wherein forming a plurality of columns froma plurality portions of the preliminary film comprises: exposing theplurality portions of the preliminary film to plasma radicals having afirst power to transform the plurality portions of the preliminary filmto the plurality of columns; and exposing the other portions of thepreliminary film to plasma radicals having a second power, the secondpower lower than the first power.
 17. The method of claim 13, whereinforming a plurality of columns from a plurality portions of thepreliminary film comprises: exposing the plurality portions of thepreliminary film to a first type of plasma radicals to transform theplurality portions of the preliminary film to the plurality of columns;and exposing the rest of the preliminary film to a second type of plasmaradicals, the second type of plasma radical different from the firsttype of plasma radicals.
 18. The method of claim 13, wherein forming thelamella on top of the plurality of columns comprises: spraying a secondprecursor onto the preliminary film formed with the plurality ofcolumns; forming a layer of the second precursor on top of thepreliminary film formed with the plurality of columns; and exposing thelayer of the second precursor to an energy beam to transform the layerof the second precursor to the lamella.
 19. The method of claim 13,wherein forming a lamella on top of the plurality of columns comprises:exposing the preliminary film formed with the plurality of columns toplasma radicals, laser, or electrons to transform a top portion of thepreliminary film formed with the plurality of columns to the lamella.20. The method of claim 13, wherein forming a preliminary film on thesubstrate from the layer of the precursor comprises: exposing the layerof precursor to an energy beam to form preliminary film on thesubstrate.
 21. The method of claim 13, wherein forming a preliminaryfilm on the substrate from the layer of the precursor comprises:spraying an additional precursor onto the layer of the precursor to forma layer of the additional precursor; and exposing the layer of theadditional precursor to an energy beam to form the preliminary film onthe substrate.
 22. The method of claim 13, wherein forming a preliminaryfilm on the substrate from the layer of the precursor comprises:exposing the layer of precursor to an energy beam to form an initialfilm; spraying an additional precursor onto the fi initial film to forma layer of the additional precursor; and exposing the layer of theadditional precursor to an energy beam to form the preliminary film onthe substrate.
 23. A flexible polymeric film manufactured by a methodcomprising: spraying a precursor onto a substrate; forming a layer ofthe precursor on the substrate; exposing the layer of the precursor toan energy beam to form a preliminary film on the substrate; forming aplurality of columns from a plurality portions of the preliminary film,the plurality of columns more rigid than other portions of thepreliminary film; and forming a lamella on top of the preliminary filmformed with the plurality of columns.